Process for mordanting and dyeing of wool



Patented Nov. 19, I929 want 1:.

CHARLES SAMUEL isnnronnor LEEDS, nnemiun PROCESS FOR MORDANTING'AND D'YEING or wooL' p I No Drawing. Application filed January 15, 1926, Serial No. 81,589, and in Great Britain April 23, 1925.

This invention relates to processes for mordanting wool and has for its object an improved process for mordanting wool with chromium salts.

According to this invention I perform the mordanting of wool with chromium salts in such a manner as to efi'ect the total reduction of the bichromate employed to the state of chromium hydroxide. In this form the mordant gives the fastest shades to light,milling and potting with colouring matters capable of being dyed on chrome mordant, and in most cases the shades produced are brighter and more intense than when the'ordinary processes of mordanting areemployed.

As a reducer of bichromate in presence of I p a,

' after mlnutes I add gradually during 30 the wool I employ the salts of thiosulphuric acid, preferably on account of costthe sodium salt, sodium thiosul termed sodium hyposulphite.

When this salt is acted upon by dilute acids it decomposes yielding sulphur (at first in the colloidal state) and sulphurous acid. These substances, exert a reducing action on the bichromate, being in turn oxidized to sulphuric acid. Sulphites or bisulphites can not be employed instead of the thiosulphates in my process. At the boiling temperature they are uncontrollable and too energetic in their action, so that irregular and uneven results are obtained. For the purposes of my invention a thiosulphate must be used.

In mordanting wool I proceed according to one of the two following methods V Ewample 1 For 500 lbs. loose wool in adyeing machine through which hot water is circulating I add 10 lbs. of bichromate of soda in strong solu- 46 tion whilst the mordant bath is at 60 C. or

thereabouts. Circulation is continued and the temperature gradually raised. After 20 minutes and whilst the temperature is about 90 to 93 C. I add gradually 15 lbs. sulphuric acid diluted with water. Boiling is continued for further 20 minutes, then I add gradually a solution of 5 lbs; sodium thiosulphate. After 30 minutes further boiling the bath will be found to be free from chrome 50' salts.

strong solution whilst the bath is at C and-with the Winch running. The tempera phate, sometimes In order to render the action of the thiosulphate more certain, and to preventany, riskof sulphur being deposited, I find'it-is beneficial to add to the mordantingbath along with the thiosulphate to of boraxQ on the weight of the wool, or to 1% of sodium acetate, These additions certainly enable the mordanting to be performed with greater regularity and'in'less time. I

Example 2 machine I add 10 lbs. bichromate of soda in ture is gradually raised to to C. and

minutes 15% lbs. sulphuric acid diluted with water. An addition of 5 to 5%.lbs. sodium .thiosulphatepand1 A; to 2 lbs. of borax is Y then made, and the boiling continued until all chrome-is fixed on the fibre. 1 2 to 5 lbs. of sodium acetate may be substituted for 1 borax. n

The mordant thus fixed is sufiiciently basic for most purposes of dyeing, but when chro- J mium hydrate only is required the smallproportion of acid groups in combination hydroxide mordant, the wool prepared as above. is then treated in the same or in a separate bath at 60 to 93 C; with an addi tion of mild alkali suchas sodium carbonate or ammonia suflicient to bring about a neutral condition when it is ready fordyeing. 'Ihe dyeing may beconducted in the same (sequence dyeing) or in a separate bath.

In most cases the dyeing can'be started at once by addition of'the dye to the hot neutral or slightly alkaline bath, when in the case of hematine the colouring matter will commence dyeing the fibre, in other cases the addition of a weak acid is necessary to start the dyeing. As a simplification I mix sodium carbonate with the dye to be used, in quantity sufficient to render the bath slightly alkaline after addition, and when the hydroxide mordant has been properly dyebath.

formed I gradually add acetic, lactic or formic acid to give an acid reaction to the My invention includes'the dyeing of the wool which can follow the mordanting'in the same vessel in sequence, with consequent saving in steam, labour and time. 7

Sequence dyeing is found extremely useful for compound blacks using hematine along with such fast blacks'as Durachrome Black A, Eriochrome Blacks A & T, and

' Diamond Black P. V. 7

Diamond Black P. V. is however an afterchrome colour, and inusing it and other afterchrome colours I proceed as follows The wool is first dyed with say 4% of the exhaustion is complete 2% bichroinate of soda is added and boiling is continued for 7 further 40 minutes, then 2% of concentrated sulphuric acid containing 96% H 550 followed by 1% thiosulphate are gradually until the added, and the boiling continued 4% hema- ;bath is exhausted of chrome salts.

tine crystals containing 10% sodium carbonate are then added, and finally towards the end of the dyeing sufficient acetic acid to give an acid reaction.- 7 e What I claim and desire to secure by Letters Patent is 1. A process for chrome mordanting wool so that all the chrome is withdrawn from the mordanting bath and fixed upon the wool, leaving the bath fit for use in a dyeing operation by treating the wool in a boiling bath leaving the bath fit for use in a d eing opera- 7 tion by treating the wool in a oiling bath with a bichromate and sodium thiosulphate and borax in the presence of a little acid, and

then dyeing the wool with a mordant dyeing color in the same bath.

In'testimony whereof, I aflix myjs gnature CHARLES SAMUEL BEDFORD.

V colouring material and-2% concentrated-sulphuric acid containing 96% i with a bichromate andsodium thiosulphate V and a mild alkali as a regularizing agent 1n 1 the presence of a little acid.

2. A process for chrome mordanting wool 3. A process for chrome mordanting wool so that all'the chromeis withdrawn from the i mordanting bath and fixed upon the wool,

leaving the bath fit for use ina dyeing operation by treating the wool in a boiling bath with a bichrom'ate and sodium thiosulphate and borax inthepresence of a little acid;

4. A process for chrome-mordanting wool :so that all the chrome is withdrawn from the mordanting bath and fixed upon the wool,

leavingthe bath fit for use in a dyeing operation by treating the wool in a boiling bath with abichromate and sodium thiosulphate and borax in the presence of a little acid, and then dyeing the wool with a mordant dyeing color. a

a 5. A process for chrome mordanting wool so that all the chrome is withdrawn from the imordan-ting bath and fixed upon the. wool, 

